File size limit for syncing

In any SharePoint library, you can sync files of up to 2 gigabytes (GB).

Invalid characters for SharePoint Online

The following characters in file or folder names aren't supported when you sync: , /, :, *, ?, ', <, >, , # , %

Additionally, a file or folder name that begins with a tilde (~) isn't supported.

Invalid characters for SharePoint Server 2013

The following characters in file names aren't supported when you sync: , /, :, *, ?, ', <, >, , #, {, }, %, ~, &
Additionally, a file name that begins with a period (.) or a tilde (~) isn't supported.

Invalid file types

You can't upload files that have the following extensions: *.tmp or *.ds_store
You can't upload the following files: desktop.ini, thumbs.db, ehthumbs.db
Additionally, you can't upload files whose file types are blocked on the SharePoint on-premises site. If your organization is running SharePoint Server, the list of blocked files may vary, depending on what your administrator sets up. If your organization is running SharePoint Online, there are no blocked file types. To see a list of the default blocked files, go to File types that cannot be added to a list or library.

Number of items that can be synced

You can sync up to 20,000 items total across all synchronized libraries. This includes OneDrive for Business libraries, Team Site libraries, or both. This includes folders and files. Separately from the overall sync limit, there are limits to the number of items that can be synchronized for each library type.

• You can sync up to 20,000 items in a OneDrive for Business library. This includes folders and files.

• You can sync up to 5,000 items in a SharePoint library. This includes folders and files. These are libraries that you find on various SharePoint sites, such as team sites and community sites, libraries that other people created, or that you created from your Sites page. You can sync multiple SharePoint libraries. Any team sites that you sync will also count against the overall 20,000 item limit across all synchronized libraries.

Character limit for files and folders

These limits apply to files and folders that you add to a synced library folder for uploading to SharePoint. These limits apply to un-encoded URLs, they don't apply to encoded URLs.

• In SharePoint Server 2013, file names can have up to 128 characters.

• In SharePoint Online, file names and folder names can have up to 400 characters.

Unsupported folder names

When you sync OneDrive for Business with SharePoint Online or SharePoint 2013, the following folder name isn't supported at the root level for a list or library: forms

This occurs because 'forms' is a hidden default folder that's used to store templates and forms for the library.

Additionally, a folder that contains the following string is reserved by SharePoint, and isn’t supported: _vti_

The following folder names can be synchronized in OneDrive for Business and SharePoint Online. However, if they’re synchronized, they may not appear when you view the library on the SharePoint Online or OneDrive for Business webpage. With some of these restrictions, you may be unable to add files or folders that have these characters while in the OneDrive for Business folder. However, if you create the files or folders outside OneDrive for Business and then drag those files or folders into the OneDrive for Business folder, the files and folders will sync but the files won't appear on the webpage.

• *_files,

• *_Dateien

• *_fichiers

• *_bestanden

• *_file

• *_archivos

• *_tiedostot

• *_pliki

• *_soubory

• *_elemei

• *_ficheiros

• *_arquivos

• *_dosyalar

• *_datoteke

• *_fitxers

• _failid

• *_fails

• _bylos

• *_fajlovi

• *_fitxategiak

• *_private

• *_t

• *_w

Shared with Me

You can't synchronize the Shared with Me view grouping of files from a OneDrive for Business site.

Open files

Any file that’s currently open by an application (for example, an Excel .xlsx file) can't be synced by OneDrive for Business. To sync the file, close any application where the file is currently being used, and then sync the file.

GUID strings as file names

The GUID string structure is supported in SharePoint Online.
The following GUID string structure isn't supported for file names in SharePoint 2013:

• '{' + 8 hexadecimal + '-' + 4 hexadecimal + '-' + 4 hexadecimal + '-' + 4 hexadecimal + '-' + 12 hexadecimal +'}'

For example, a GUID that matches this structure resembles the following:

• {9b6634a7-26b7-40a2-a48e-6f967d89c29e}

Outlook PST files

Whereas PST files aren’t actively blocked by OneDrive for Business, syncing PST files that are in an open state isn’t supported. If you decide to sync PST files (for example, an archive PST file that you don’t load or view in Outlook), they can’t be in an open state at any time by any application while they’re in the OneDrive for Business sync folder. A PST file that’s connected to Outlook will be updated regularly and therefore if synchronized, can result in too much network traffic and growth of the Office File Cache on your local drive.

If you want to move your Outlook .PST Data File, read How to remove an Outlook .pst data file from OneDrive.

OneNote notebooks

Because OneNote notebooks have their own sync mechanism, they aren't synced by the OneDrive for Business sync client. You can upload OneNote notebooks to a SharePoint Online page. However, they won't sync with through the OneDrive for Business sync client application. Additionally, if you add a OneNote notebook to a local folder that syncs with SharePoint Online, the notebook won't sync with the SharePoint site and may cause other sync errors within the local folder.

Learn Move a OneNote for Windows notebook that you've shared with others

OneNote Class Notebooks

If you're using a license from an Office 365 Education SKU, you may be able to create a OneNote Class Notebook. When you create that Class Notebook, OneDrive for Business isn't able to sync. To resolve this issue, download and enable the Next Generation Sync Client for OneDrive for Business. To do this, go to Improve your OneDrive sync experience.

Lookup columns in a library

The SharePoint Online or OneDrive for Business library can't exceed the lookup column threshold. For more information, go to 'We couldn’t sync this library' error when you use the OneDrive for Business sync client.

Profile type limitations

The OneDrive for Business sync app isn’t supported on a computer that uses one of the following profile types:

• Roaming

• Mandatory

• Temporary

Additionally, the OneDrive for Business sync app isn’t supported for client sessions that are hosted on Windows 2008 Terminal Services or Windows 2012 Remote Desktop Services (RDS).
For more information, go to OneDrive for Business sync app doesn’t finish installing, or setup runs every time that you sign in to your Windows profile.